Providing a unified network for handling both digital communications and electrical power distribution across the electrical system of a vehicle or other artificial structure is the goal of many developers. The character of the physical connectivity elements connecting the various electrical/electronic devices comprising the networked electrical system is of great interest. Preferably, the physical connectivity elements will facilitate simplified construction, maintenance and modification of the networked electrical system with respect to both the data communications and power distribution aspects.
Conventional vehicle electrical systems, for example, those used in production automobiles, typically distribute electrical power using wiring harnesses featuring dedicated wire circuits running from each discrete electrical/electronic device to its associated power source and/or control switch. Further, most conventional vehicle wiring systems utilize physically separate power conductors and (when needed) signal conductors. Such conventional wiring systems are typically model-specific, feature limited (if any) networking capabilities, and offer no overall control and data collection functions. Thus, such wiring systems are not readily amenable to integrated network communication and power distribution. Furthermore, once production has started, modifying a wiring system utilizing a fixed wiring harness can be very difficult and expensive.
Another drawback of conventional vehicle electrical systems is the widespread practice (especially common in the automotive domain) of using the vehicle's chassis or frame as a common neutral (i.e., ground) connection for electrical circuits. This practice dates back to the early days of automotive development, and has likely been perpetuated for reasons of cost-containment. However, using a vehicle's frame or chassis as a ground or neutral connection may cause problems. First, ground connections to the vehicle's frame or chassis tend to become loose over the life of a vehicle. Such loose ground connections result in voltage drops across the degraded connection, thus interfering with the power distribution aspect of the system. Further, loose ground connections may also generate electromagnetic noise, which may be picked up as “static” by other subsystems in the vehicle, such as the vehicle's radio or sound system. Such electromagnetic noise may also interfere with the operation of network communications if a data network is present on the vehicle.
To the extent that microcontrollers and other electrical/electronic components are currently interconnected in vehicles, the interconnection is typically done via either device-specific local busses (e.g., across an instrument panel), or through proprietary low-rate busses such as those utilizing the Controller Area Network (CAN) protocol. Such interconnections are expensive to engineer and typically rely on proprietary architecture and software. Further, they are not generally capable of supporting integrated diagnostics, fault detection and maintenance related data collection due, at least in part, to limited data transmission rates.
In order to better integrate the numerous electrical devices, sensors and controls used in modern vehicles into a network, higher data transmission rates are required. Better data transmission rates may also allow individual devices to be sequentially connected, (e.g., “daisy chained”) together for high level control and monitoring with a host computer. Also, the elimination of electromagnetic noise is important in order to achieve the desired data transmission rates.
Although the high-speed networking of computers is well known using standard networking physical connectivity methods such as “Ethernet over twisted pair,” including the widely used 10Base-T, 100Base-T and 1000Base-T (Gigabit Ethernet) methods, these physical connectivity solutions are inadequate for networking the majority of electrical/electronic devices comprising the electrical system of vehicles, e.g., production automobiles. This is because they generally cannot fulfill the power distribution aspect. For example, the Category 5, 5e and 6 cable typically used for 10Base-T, 100Base-T and 1000Base-T physical connectivity has inherently limited electrical power capacity that is insufficient to reliably handle high-current devices found in vehicles, e.g., automotive DC electric motors, electromagnetic clutches, solenoids, lighting, etc. Even enhanced power-delivery schemes such as Power Over Ethernet (POE) cannot typically supply sufficient power for vehicle-wide networking of the electrical system.
Thus, there exists a need for a hybrid cable that provides physical connectivity in a networked electrical system and fulfills both the data communications aspect and the power distribution aspect of the networked system.